JPH04363971A - Coding/decoding processing method - Google Patents

Abstract

PURPOSE:To implement reception and transmission preparation at a high speed with simple constitution by operating coding/decoding while a line memory is selected. CONSTITUTION:The method is provided with a binary data input terminal 1, a coding exclusive line memory 2, a coding decoding common use memory 3, a coding circuit 4, a code output terminal 9, a coding input terminal 6, a decoding circuit 7, a decoding exclusive line memory 8, a binary data output terminal 9 and changeover switches S1-S6. Then the coding exclusive line memory 2 and the decoding exclusive line memory 8 are operated while being selected by using the changeover switches S1-S6, the coding decoding common use memory 3 is used in time division to implement coding/decoding in time division. Thus, the utilizing efficiency of the memory is enhanced and high speed operation is attained with simple constitution.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides an encoding and
The present invention relates to a decoding processing method.

(Prior Art) In order to encode and transmit images that are two-dimensionally scanned, read, and recorded like a facsimile, adjacent scanning is used as a high-efficiency encoding method that suppresses redundancy and compresses the amount of data bits. There is a known method of encoding and decoding by referring to line bit data and utilizing correlation.

For example, the MR (Modified READ) encoding method is widely used as a highly efficient two-dimensional encoding method, in which the pixels of the previous scanning line as a reference line change from the black level to the white level, or conversely, the white level. Regarding the deviation between the position on the main scanning line where the black level changes from black level and the current encoded line, the size of the deviation and the context are classified for each change point, and the corresponding code is written. This is used in conjunction with the MH code, which is a one-dimensional encoding method, to perform data compression.

When decoding data encoded in this manner, it is necessary to refer to the data decoded for the previous line. Therefore, in both encoding and decoding, it is essential to refer to the immediately preceding line of data.

Preparing for transmission while receiving a facsimile is advantageous in terms of device availability. However, if the line memory is shared when preparing for transmission during reception, the decoding and encoding operations are performed alternately in a time-sharing manner, so the line memory that stores the decoded binary data is , are erased during encoding, and binary data captured during encoding is also erased during decoding. To do this, it is necessary to prepare expensive page memory or use a dedicated line memory when decoding, and when encoding, data from the previous line must be stored in the line memory each time. I had to load it into .

Therefore, there are problems in that a page memory with a large memory capacity is required, and that it takes time to read the data of the previous line into the line memory each time the reception operation and the transmission preparation operation are switched.

(Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned circumstances, and aims to realize an encoding/decoding processing method that improves memory usage efficiency and enables high-speed operation with a simple configuration. The purpose is to

(Means for Solving the Problems) The present invention provides an encoding/decoding processing method for encoding/decoding image data with reference to a previous scanning line. , and an encoding/decoding shared memory, and is characterized in that encoding and decoding are performed in a time-sharing manner by using the encoding/decoding shared memory in a time-sharing manner.

(Embodiment) FIG. 1 is a schematic configuration diagram for explaining an embodiment of the encoding/decoding processing method of the present invention. In the figure, 1 is a binary data input terminal, 2 is an encoding-only memory, 3 is an encoding/decoding shared memory, 4 is an encoding circuit, 5 is a code output terminal, 6 is an encoding input terminal, and 7 is a decoding terminal. 8 is a memory dedicated to decoding, 9 is a binary data output terminal, and S1 to S6 are changeover switches.

Note that the changeover switch is shown as a switch for the sake of convenience, and is usually constructed from a logic circuit.

The reception operation and the transmission preparation operation are performed while switching the changeover switches S1 to S6.

First, the reception operation will be explained.

As shown in FIG. 1(A), the changeover switches S1 and S2 are switched to the b side, and the binary data input terminal 1 and the encoding-only memory 2 are disconnected. Changeover switch S4, S5
, S6 are switched to the a side. The coded data input to the coding input terminal 6 is decoded into binary data by the decoding circuit 7, stored in the coding/decoding shared memory 3, and passed through the changeover switches S4 and S5. The value data is taken out to the output terminal 9. During this decoding,
The data stored in the decoding-only memory 8 becomes reference data.

To decode the next line, as shown in FIG. 1(B), changeover switches S4 to S6 are switched to the side. Since the reference data obtained by decoding the previous line is in the encoding/decoding shared memory 3, the encoded data from the encoding input terminal 6 is decoded using this as reference data. decrypted 2
The value data is stored in the decoding-only memory 8, and is also sent to the binary data output terminal 9 via the changeover switches S4 and S5.
It is taken out.

By repeating the operations shown in FIG. 1(A) and FIG. 1(B), decoding is sequentially performed line by line.

Preparations for transmission can be made during this reception.

When a document is inserted into the device and a reading operation is performed, the image data is read as binary data, applied to the binary data input terminal 1, encoded, and stored in a RAM (not shown) as encoded data.

The encoding starts from the state shown in Fig. 1(B) to the state shown in Fig. 1(C).
). In this state, selector switches S4 and S5
is switched to the b side, and S6 is switched to the a side. The changeover switches S1 and S3 are switched to the a side, and the binary data of the first line is DMA-transferred to the encoding/decoding shared memory 3.
One pixel is input to the encoding circuit 4 as the current line for each pixel period. On the other hand, data in the encoding-only memory 2 is also input to the encoding circuit 4 as a reference line, one pixel at a time for each pixel period. For the first cycle, the encoding-only memory 2 only needs to be initialized with all bits being 0 or 1 for reference. The encoding circuit 4 takes in the data of the current line and the reference line every pixel period, encodes it, and outputs it to the code output terminal 5.

For the next line, as shown in FIG. 1(D), changeover switches S1 to S3 are switched to the side, the input data is DMA-transferred to the encoding-only memory 2, and then stored in the encoder-decoder shared memory 3. The data of the previous line that is displayed is encoded as reference line data.

Through this operation, two lines of image information are encoded, and the last line of binary data is stored in the encoding-only memory 2.

From this state, return to FIG. 1(A), perform a receiving operation, and then perform decoding in the state of FIG. 1(B), thereby decoding two lines of encoded data.

Thereafter, the reception operation and the transmission preparation operation are performed on a time-division basis for two lines at a time, so that encoding and decoding processing can be performed at high speed. The data read in the transmission preparation operation can be transmitted after the reception operation is completed. After receiving,
If you can set a transmission reservation so that it will be sent automatically, you can perform automatic transmission just by setting the scanning of the transmission document.

Although the data has been described as serial data, it may be serial or parallel by appropriately providing a serial/parallel conversion circuit in accordance with the configuration of the memory, the encoding circuit 4, the decoding circuit 7, etc.

When switching the encoding mode and decoding mode as described above, the current data is stored in the encoding-only memory 2 and the decoding-only memory, as shown in FIG. 1(B) and FIG. 1(D). By doing this in the same state as the line, each can be used as a reference line for the next operation. Therefore, it is clear that encoding and decoding are not limited to two lines at a time, but may be performed for even lines at a time.

(Effects of the Invention) As is clear from the above description, according to the present invention, in a facsimile machine, by operating the line memory while switching, the reception operation and the transmission preparation operation can be performed at high speed with a simple configuration. The effect is that it can be done.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram for explaining an embodiment of the encoding/decoding processing method of the present invention. 1...Binary data input terminal, 2...Encoding dedicated memory, 3...
Encoding/decoding shared memory, 4... Encoding circuit, 5... Code output terminal, 6... Encoding input terminal, 7... Decoding circuit, 8... Decoding dedicated memory, 9... Binary data output terminal, S1 to S6
...Choice switch.

Claims (1)

[Claims] An encoding/decoding processing method that encodes/decodes image data by referring to a previous scanning line, which includes a line memory dedicated to encoding, a line memory dedicated to decoding, and a shared memory for encoding/decoding. An encoding/decoding processing method characterized by performing encoding and decoding in a time-division manner by using a shared memory for encoding and decoding in a time-division manner.